Gas turbine engine turbine blades are exposed to high temperatures and can experience excessive wear in certain operating conditions. In some cases, this wear has been known to result in fractures occurring in the blades. One cause of such excessive wear is hot-corrosion.
Hot-corrosion, sometimes called “sulphidation”, is a phenomenon whereby accelerated degradation of the turbine blade occurs. This may be caused by the operating conditions to which the components are exposed, environmental impurities on the metal surface, or a combination of these and other factors. Regardless, the result can be a rapid degradation of the underlying alloy of the metal turbine blade.
Attempts have been made to minimize the effect of hot-corrosion through the application of protective coatings. It is known, for example, to apply a protective coating made of platinum aluminide on the entire exterior surface of the airfoil. Typically, such a platinum aluminide coating is applied by diffusion to all external and internal surfaces of the airfoil. However, the added weight caused by this coating (due to the density of the aluminide material and/or the thickness of this coating that is required, and its application over the entire airfoil) subjects the turbine blades to increased stresses, which can further reduce the lifespan of the part. This is undesirable.
Accordingly, there exists a need for an improved turbine blade and a method of protecting such turbine blades from hot-corrosion.